1. Field of the Invention
The invention relates to a vehicle control apparatus and a vehicle control method.
2. Description of the Related Art
There are hybrid vehicles that include a motor generator, which serves as, an electric motor and a generator, in addition to an internal combustion engine (engine). In the hybrid vehicles, the internal combustion engine is operated at highest possible efficiency, and the motor generator compensates for a shortfall in a drive power or an engine braking force.
An example of such hybrid vehicles is described in Japanese Patent Application Publication No. 2004-345527 (JP-A-2004-345527). In the hybrid vehicle described in JP-A-2004-345527, the shift mode is switched between the continuously variable shift mode and the stepped shift mode. The hybrid vehicle includes a power split mechanism that is formed by combining, for example, two planetary gear mechanisms with each other. The power split mechanism is connected to an engine, a first motor generator, a drive shaft and a brake, and a second motor generator is connected to the drive shaft. When the brake is released, the engine speed is continuously adjusted by continuously adjusting the rotational speed of the first motor generator. In this case, the vehicle is driven in the continuously variable shift mode. On the other hand, when the brake is locked, the gear ratio is fixed by preventing rotation of one of the above-described rotating elements. In this case, the vehicle is driven in the stepped shift mode.
However, the drive shaft responds to the output from the engine more quickly in the stepped shift mode than in the continuously variable shift mode. Therefore, the drivability may differ between the continuously variable shift mode and the stepped shift mode.